Retrieve current or previous frontmatter setting

[remypar5]

It would be nice to have a way to determine what the frontmatter value is of (setting X) the last time it was set.

An example:
We could use it to define "sections" or "chapters" and not have to set it for any slide in that section, but rather only when it starts. We can use it to i.e. determine a default background color/blend or even display it in the bottom bar

[remypar5]

Maybe this will help